A convicted car thief from a wealthy background could be facing life behind bars for mowing down a child actor and his aunt during a police chase after admitting manslaughter charges.

Joshua Dobby, 23, was out on licence when he drove a black Ford Focus into Makayah McDermott, 10, and Rosie Cooper, 34, as they walked along Lennard Road in Penge on the afternoon of August 31 last year.

At an earlier hearing, Dobby admitted causing death by dangerous driving and injuring Makayah's sister but denied manslaughter.

Ahead of his trial, he changed his plea on Thursday, admitting two counts of manslaughter and also pleading guilty to dangerous driving relating to an incident on August 26 on the A228 near Snodland in Kent.

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Death by dangerous driving carries a maximum sentence of 14 years in prison but, in an unusual move, the Crown also brought manslaughter charges.

It means that, following consideration of Dobby's potential danger to society, a judge has the option of imposing a discretionary life sentence.

When he first appeared before magistrates in Bromley last September, the court heard that Dobby had a "very long previous criminal record" including aggravated vehicle-taking.

He was brought before the courts just two months before the deaths of Makayah and his aunt and was on licence at the time, the court was told.

News Shopper: Makayah McDermott, 10, who was killed along with his aunt by a car being chased by police in Penge, south-east London (BAM/PA)

Makayah McDermott was killed in the crash. Photo: OnPoint Headshots​

During his last appearance at the Old Bailey, Robin Ghosh, for Dobby, had said: "He wishes it to be noted that he fully acknowledges the utterly incomprehensible pain and suffering caused to the families involved."

Members of the victims' families sat in the well of the court to watch the hearing before Judge Nicholas Hilliard QC.

At the time of his death, Sam Brown, of entertainment agency Brown and Mills, described Makayah as an "extremely talented young actor" and a "bright young star".

He had recently auditioned for a role in a television series and had featured in a number of commercials.

Hairdresser Ms Cooper was hailed by a friend as "one of the kindest, most beautiful, caring people you would ever meet".

The case comes amid discussions about giving judges greater sentencing powers when dealing with the worst death by dangerous driving offenders.

Dobby entered his guilty pleas via video link from jail.

Judge Hilliard ordered a pre-sentence report on his dangerousness and adjourned sentence to Friday March 10.

He said it was clear Dobby was driving dangerously in August 26 last year and again on the day of the fatal crash on August 31.

He went on: "There is also an incident in 2010 that ended in a collision.

"I understand he was on licence at the time of this offence and on the face of it he had a serious drug problem."

He said the defendant's drug issues were shown in a letter to his girlfriend.

However, he confirmed the Crown's case was that toxicology texts were unable to establish whether he was under the influence of drugs at the time of the crash, only that he had used them previously.